Background

When objects are not moving or moving at a constant speed, the forces on them are balanced. We are going to try and balance the force of gravity and the force from a hair dryer’s air stream on a table tennis ball.

You will need

• 1 Table tennis ball
• 1 Hair dryer

What to do

1. Point the hair dryer upwards and turn it on.
2. Carefully place the table tennis ball in the air stream.
3. The table tennis ball should float in the hair dryer’s air stream.
4. You might have to play with the strength of the air flow to get things exactly right.
5. If you get it to work, try to tilt the hair dryer and see how far you can tilt it, before the ball falls off.
6. When the table tennis ball is floating the forces of the hair drier’s air stream and gravity are exactly balanced.

You can also watch this experiment on YouTube: